ACT8840
Rev 2, 29-Jan-15
ALWAYS-ON LDO (REG13)
General Description
REG13 is an always-on, low-dropout linear
regulator (LDO) that is optimized for RTC and
backup-battery applications. REG13 features low-
quiescent supply current, current-limit protection,
and reverse-current protection, and is ideally suited
for always-on power supply applications, such as
for a real-time clock, or as a backup-battery or
super-cap charger.
Reverse-Current Protection
REG13 features internal circuitry that limits the
reverse supply current to less than 1µA when the
input voltage falls below the output voltage, as can
be encountered in backup-battery charging
applications. REG13's internal circuitry monitors the
input and the output, and disconnects internal
circuitry and parasitic diodes when the input voltage
falls below the output voltage, greatly minimizing
backup battery discharge.
Typical Application
Voltage Regulators
REG13 is ideally suited for always-on voltage-
regulation applications, such as for real-time clock
and memory keep-alive applications. This regulator
requires only a small ceramic capacitor with a
minimum capacitance of 0.47μF for stability. For
best performance, the output capacitor should be
connected directly between the output and GA, with
a short and direct connection.
Figure 4:
Typical Application of RTC LDO
Backup Battery Charging
REG13 features a constant current-limit, which
protects the IC under output short-circuit conditions
as well as provides a constant charge current, when
operating as a backup battery charger.
Innovative PowerTM
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